Computer-aided diagnosis (CAD) systems help doctors to diagnose diseases by analyzing medical images, such as ultrasound images, and by displaying abnormal portions in the medical images based on the analysis. Such CAD systems may reduce diagnosis uncertainty caused by a human's limited ability to detect, and may also reduce doctors' heavy workload in reading each medical image.
A main task used in the analysis of medical images and in the CAD system is accurate and effective detection of lesion areas from medical images. To this end, various algorithms are used, in which algorithms mainly used for image processing or data analysis processing in other technical fields are used as a measure to evaluate detection accuracy of detected lesion areas. However, such measure may not reflect characteristics of medical images.